Hip Joint Device

ABSTRACT

A locking member for implantation in a hip joint of a patient is disclosed. The locking member is adapted to assist in the fixation of a medical device, having an artificial hollow caput femur surface, to the collum and/or caput femur, wherein the artificial caput femur surface comprises at least one extending portion adapted to clasp a portion of the caput and/or collum femur. The locking member comprises an element adapted to lock the artificial caput femur surface such that the caput femur remains clasped and restrained in the artificial caput femur surface.

TECHNICAL FIELD

The present invention relates generally to medical devices forimplantation in a hip joint.

BACKGROUND ART

The hip joint is a synovial joint, joining the pelvis to the proximalportion of the femoral bone. Synovial joints are the most common typesof joints in mammals, and are typical of nearly all limb joints. Thecontacting surfaces of said the pelvic, the acetabulum, and thecontacting surface of the femoral bone, the caput femur, are smooth androunded, and covered by articular cartilage. A synovial membrane,encapsulates the joint, forming a hip joint cavity, which containssynovial fluid. Outside the synovial membrane is a fibrous capsule andligaments, forming an articular capsule.

There are both natural and pathological processes leading todeteriorated joint function. With age and wear, the articular cartilagebecomes less effective as a shock absorber and a lubricated surface.Different degenerative joint diseases, such as arthritis,osteoartrithis, or osteoarthrosis, accelerate the deterioration.

Hip joint Osteoarthritis is a syndrome in which low-grade inflammationresults in pain in the hip joints, caused by abnormal wearing of theCartilage that acts as a cushion inside if the hip joint. This abnormalwearing of the cartilage also results in a decrease of the jointslubricating fluid called Synovial fluid. Hip joint Osteoarthritis isestimated to affect 80% of all people over 65 years of age, in more orless serious forms.

The present treatment for hip osteoarthritis comprises NSAID drugs,local injections of Hyaluronic acid or Glucocorticoid to helplubricating the hip joint, and replacing parts of the hip joint with aprosthesis through hip joint surgery.

The replacing of parts of the hip joint is one of the most commonsurgeries to date performed at hundreds of thousands of patients in theworld every year. The most common method comprises placing a metalprosthesis in Femur and a plastic bowl in Acetabulum. This operation isdone through an incision in the hip and upper thigh and through FasciaLata and the lateral muscles of the thigh. To get access to the joint,the supporting Capsule attached to Femur and Ilium needs to bepenetrated, making it difficult to get a fully functional joint afterthe surgery. Femur is then cut at the neck with a bone saw and theprosthesis is placed in femur either with bone cement or without.Acetabulum is slightly enlarged using an Acetabular reamer, and theplastic bowl is positioned using screws or bone cement.

The complications after hip joint surgery includes dislocation of thehip joint and loosening of the prosthesis from its fixation in thefemoral bone. The loosening and/or dislocation of the prosthesis couldbe induced by an abnormal strain being placed on the hip joint from e.g.the patient falling or making a rapid movement of the hip, or by abodily macrophage reaction.

SUMMARY

A locking member for implantation in a hip joint of a patient isprovided. The locking member is adapted to fixate a medical devicecomprising an artificial hollow caput femur surface to a caput femur hipjoint surface. The locking member comprises a loop-shaped element with afirst and a second end adapted be mechanically connected using anengagement member, so that it forms a closed loop-shaped element with acircumference encircling the caput femur or collum femur.

According to one embodiment, the loop-shaped element is adapted to beconnected in at least a first and second locking position. Theloop-shaped element could have a first inner circumference, when theloop-shaped element is connected in the first locking position, the loopshaped element has a second smaller inner circumference, when the loopshaped element is connected in the second locking position. This way thelocking member could be adapted for the particular patient.

According to another embodiment the loop-shaped element is furtheradapted to be connected in a third locking position. The loop-shapedelement has a third inner circumference, when connected in the thirdlocking position, being smaller than the first and second innercircumference.

According to yet another embodiment, the locking member could further beadapted to be arranged in an area extending a distance beyond themaximum diameter of the caput femur.

The engagement member could according to one embodiment comprise a firstand a second engagement member part arranged at said first and secondlocking member end, respectively.

The first and second engagement member could be adapted to mechanicallyself connect by introducing the first engagement member into the secondengagement member. According to one embodiment the first and secondengagement member parts could have the shape of protrusions extendingfrom the first and second locking member ends. The first and secondengagement member could extend axially from the first and second lockingmember ends to form a horizontally arranged gripping claw.

According to yet another embodiment, the first and second engagementmember extends radially from the first and second locking member ends,to form a vertically arranged gripping claw.

The locking member, according to any of the embodiments, could comprisesa first engagement member part having the shape of a protrusionextending from the first locking member end and said second engagementmember part has the form of at least one recess or hole.

According to yet another embodiment the first and second ends of thelocking member could be connected by using an engagement membercomprising two pivotable locking parts.

According to yet another embodiment, the first locking part could bepivotably attached both to the first end of the locking member and tothe second locking part.

The second locking part could, according to one embodiment be attachedto the first locking part in an engagement point arranged between theouter ends of the first locking part.

According to yet another embodiment the second locking part could beattached to the first locking part in a point arranged substantially inthe middle of said the locking part.

According to yet another embodiment, the second locking part could beadapted to engage with a protruding part arranged in the second end ofthe locking member.

The first and second locking member ends could be adapted to be pulledtogether by pivoting the first locking part around its engagement pointin the first end of the locking member.

According to yet another embodiment, the first and second locking memberends could be arranged overlapping each other when locked together.

According to yet another embodiment the first and second locking memberends are arranged end to end when locked together.

A medical device system for implantation in a hip joint of a patient isfurther provided. The hip joint has a caput femur hip joint surfacepartly being the contacting surface of the hip joint, the hip jointfurther having a collum femur, having a first axial distribution leadingto a caput femur. A center axis of the first axial distribution of thecollum femur and the caput femur is the caput femur center axis, and thecollum femur is placed more distal than caput femur. The medical devicecomprises: an artificial caput femur surface being hollow, having amajor opening adapted to be directed towards the caput femur or asurgically modified caput femur. The artificial caput femur surface isadapted to replace a caput femur hip joint surface. The artificial caputfemur surface further has a medical device caput center axis passingthrough the major opening, being aligned with the caput femur centeraxis, when the medical device is implanted in a functional position inthe hip joint. The medical device comprises a central part and asurrounding part, the central part being aligned with the medical devicecenter axis and the surrounding part surrounding the surface of thecaput femur or the surgically modified caput femur, not including thecentral part. The medical device further comprises an inner surfaceadapted to have a first distal distance extending perpendicularly fromthe medical device caput center axis to the inner surface of thesurrounding part of the artificial caput femur surface. The first distaldistance is shorter than a second proximal distance extendingperpendicularly from the medical device caput center axis to the innersurface of the artificial caput femur surface, the second proximaldistance extends from a more proximal position on the medical devicecaput center axis than the first distal distance, being the secondproximal distance, when the artificial caput femur surface is implantedin the functional position in the hip joint. The medical device systemfurther comprises a locking member adapted to fixate the medical deviceto the caput femur, the locking member comprises a loop-shaped elementwith a first and a second end adapted be mechanically connected using anengagement member so that it forms a closed loop-shaped element with acircumference encircling the caput femur or collum femur. The hollowartificial caput femur surface could be adapted to at least partly coverthe caput femur or at least partly cover a surgically modified caputfemur, when implanted in a functional position in the hip joint.

According to yet another embodiment the artificial caput femur surfacecould be adapted to be placed in an acetabulum bowl, or an artificialreplacement therefore, when implanted in the functional position in thehip joint.

According to yet another embodiment the artificial caput femur surfacecould be adapted to have a changeable first distal distance, thusadapted to be mounted onto the caput femur or surgically modified caputfemur, when implanted in the hip joint.

The artificial caput femur surface could according to anotherembodiment, be adapted to have the maximum second proximal distance,extending perpendicularly from the medical device caput center axis tothe inner surface of the artificial caput femur surface, wherein themaximum second proximal distance could be located on a part of themedical device caput center axis located more proximal than the majoropening, when the artificial caput femur surface is mounted in thefunctional position in the hip joint, wherein the artificial caput femursurface is adapted to have the closest first distal distance extendingperpendicularly from the medical device caput center axis to the innersurface of the artificial caput femur surface, could be smaller than themaximum second proximal distance, wherein the maximum second proximaldistance could be extending from the medical device caput center axismore proximal than the closest first distal distance, when implanted inthe functional position in the hip joint.

According to yet another embodiment the caput femur has a substantiallyball shaped configuration with an outer maximum radius perpendicular tothe caput femur center axis, the caput femur being placed in a bowlshaped acetabulum, having a major opening, the caput femur and theacetabulum having one hip joint surface each, placed towards andcontacting each other, the hip joint surfaces carrying weight in the hipjoint, wherein the caput femur could be placed more proximal than thecollum femur and the caput femur could be placed more distal than theacetabulum, wherein the medical device could comprise a central part anda surrounding part, the central part being aligned with the medicaldevice caput center axis and the surrounding part surrounding thesurface of the caput femur or partly surgically modified caput femursurface not including the central part, wherein the caput femur or anartificial caput femur surface, could have a maximum caput femur radiuscross-section, in which the outer maximum radius of the caput femur orthe artificial caput femur surface could be forming a circular extendingmaximum caput femur or artificial caput femur radius circle, extendingperpendicular to the caput femur center axis, defining the maximum caputfemur radius cross-section perpendicular to the caput femur center axisor perpendicular to the aligned medical device caput center axis, whenthe artificial caput femur surface is placed in said functionalposition, wherein the surrounding part of at least one artificial caputfemur surface could comprise at least one first beyond part forextending in distal direction at least partly beyond the maximumartificial caput femur surface radius cross-section, when the artificialcaput femur surface is placed in the functional position, when theartificial caput femur surface is implanted in the hip joint, wherein atleast one first beyond part could be adapted to have a closestperpendicular distance to the medical device caput center axis, beingsmaller than an inner maximum distance, extending perpendicularly fromthe artificial medical device caput enter axis to the inner surface ofthe artificial caput femur surface, when the artificial caput femursurface is placed in a functional position in the hip joint, thusadapted to create a more stable position of the artificial caput femursurface when mounted in the hip joint.

In accordance to yet another embodiment the maximum inner distance couldbe extending from one or more predefined points selected along alengthwise extending part of the medical device caput center axis, inwhich the lengthwise extending part is defined by; two cross-sections ofthe artificial caput femur surface, extending perpendicular to themedical device caput center axis, from both the distal and proximal endpoints of the part of said medical device caput center axis, in whichboth cross-sections are placed at the outer limit of the weight carryingsurface of the artificial caput femur surface, in proximal and distaldirection, respectively, wherein the part of the medical device caputcenter axis is placed between the cross-sections, the maximum innerdistance could be extending from the medical device caput center axisproximal to the major opening, wherein the lengthwise extending part ofthe medical device caput center axis could be placed more proximal thanthe major opening, when the artificial caput femur surface is mounted inthe functional position in the hip joint.

According to yet another embodiment a first distal distance could bedefined in a first position, defined by the position in distal/proximaldirection the medical device caput center axis, and an rotating angleperpendicular to the medical device caput center axis, in which thefirst distal distance could be extending from the medical device caputcenter axis, where the first distal distance in the first distaldistance position has a first value, wherein the artificial caput femursurface could be adapted to be rotatable from a first rotation positiononto the caput femur or a surgically modified caput femur and whereinthe inner surface is adapted to have a shape allowing a change of thefirst distal distance in the first distal distance position, when theartificial caput femur surface has been rotated to a second rotatingposition, wherein the first distal distance in the first distal positionin the second rotation position has a second value, and wherein thesecond value could be smaller than the first value, when the artificialcaput femur surface is mounted onto the caput femur or surgicallymodified caput femur, when implanted in the hip joint.

According to yet another embodiment the medical device could further beadapted to: have a diameter of the major opening of the hollowartificial caput femur surface, larger than the diameter of the caputfemur or a surgical modified caput femur, when introduced onto the caputfemur, and have a diameter of the major opening of the hollow artificialcaput femur surface, smaller than the diameter of the caput femur or asurgical modified caput femur, after mounting of the artificial caputfemur surface on the caput femur in the functional position thereon.

The medical device, in yet another embodiment, could further comprisesat least one slit in the artificial caput femur surface allowing thedevice to vary the diameter of the major opening, thus allowing thedevice to be mounted on the caput femur.

According to yet another embodiment the major opening could have, atleast partly, a diameter or cross sectional distance adapted to bechanged in at least one of the following ways: increase to be able tomount the medical device on the caput femur, decrease to mechanicallyfixate and enable a stable position of the medical device on the caputfemur when mounted thereon.

According to yet another embodiment the closest distance from the innersurface of the first beyond part to the medical device caput centeraxis, perpendicular to the medical device caput center axis, could beadapted to be adjustable, for allowing the diameter of the major openingto be changed. The closest distance from the inner surface of the firstbeyond part to the medical device caput center axis, perpendicular tothe medical device caput center axis, could be adapted to be adjustableby the beyond part comprising at least one of the elements selected froma list consisting of: an elastic portion, a bendable portion, a flexibleportion, a compressible portion, and a movable portion.

According to yet another embodiment the closest distance from the innersurface of the first beyond part to the medical device caput centeraxis, perpendicular to the medical device caput center axis, could beadapted to be adjusted by the locking member.

According to yet another embodiment the medical device could comprise atleast two parts adapted to be connected to each other during a surgicalor arthroscopic/laparoscopic procedure.

The artificial caput femur surface, in yet another embodiment, could beincomplete in its surface distribution.

According to yet another embodiment the at least two surface parts couldbe adapted to be mechanically connected to each other using at least oneof the following: at least one screw, at least one pin, at least oneportion of at least one of the parts adapted to be introduced into theother part, the parts being adapted to be sliding into the other part,form fitting, welding, adhesive, pin, wire, a ball mounted into a bowlbeing portions of the parts, a male portion of one part mounted into afemale portion of the other part, a key introduced into a lock beingportions of the parts, band, and other mechanical connecting members.

According to yet another embodiment the medical device could be adaptedto be fixated to the caput femur using at least one of the following: atleast one screw, at least one pin, at least one portion of at least oneof the parts adapted to be introduced into the other part, the partsbeing adapted to be sliding into the other part, form fitting, welding,adhesive, pin, wire, a ball mounted into a bowl being portions of theparts, a male portion of one part mounted into a female portion of theother part, a key introduced into a lock being portions of the parts,band, and other mechanical connecting members.

According to yet another embodiment the artificial caput femur surfacecould be adapted to be fixated to the caput femur without penetration ofthe cortex of caput femur or the femur bone.

According to yet another embodiment the medical device could be adaptedto be fixated by means of an elastic member exerting a squeezing forceon the caput femur.

According to yet another embodiment the elastic member exerting asqueezing force on the caput femur could be the locking member. In anyof the embodiments herein, the locking member could be an elementselected from: a cord, a wire and a band.

A medical device for implantation in a hip joint of a patient is furtherprovided. The hip joint has a caput femur hip joint surface partly beingthe contacting surface of the hip joint, the hip joint further having acollum femur, having a first axial distribution leading to a caputfemur, wherein a center axis of the first axial distribution of thecollum femur and the caput femur, being the caput and collum femurcenter axis. The collum femur is placed more distal than caput femur.The medical device further comprises an artificial caput femur surfacebeing hollow and having a major opening adapted to be directed distallyand being adapted to replace a caput femur hip joint surface. Theartificial caput femur surface further having a medical device caputcenter axis passing through the major opening, being aligned with thecaput and collum femur center axis, when the medical device is implantedin a functional position in the hip joint. The medical device furthercomprises a central part and a surrounding part, the central part beingaligned with the medical device center axis and the surrounding partsurrounding the surface of the caput femur not including the centralpart. The medical device further comprises: an inner surface adapted tohave a first distal distance extending perpendicularly from the medicaldevice caput center axis to the inner surface of the surrounding part ofthe artificial caput femur surface. The distal distance is shorter thana second proximal distance extending perpendicularly from the medicaldevice caput center axis to the inner surface of the artificial caputfemur surface. The second proximal distance extends from a more proximalposition on the medical device caput center axis than the first distaldistance, being the second proximal distance, when said artificial caputfemur surface is implanted in said functional position in the hip joint.The medical device further comprising a locking member for implantationin a hip joint of a patient. The locking member is adapted to assist inthe fixation of the medical device to the collum and/or caput femur. Thelocking member comprises an element adapted to lock the artificial caputfemur surface such that the caput femur remains clasped and restrainedin said artificial caput femur surface.

According to one embodiment the medical device is adapted to lock in atleast a first and a second locking position. The locking member isadapted to; in said first locking position, lock a first artificialcaput femur surface having at least one extending portion, to a firstsize caput femur and/or collum femur, and in said second lockingposition, lock a second artificial caput femur surface having at leastone extending portion, to a second smaller size caput and/or collumfemur.

According to another embodiment, the locking member is adapted to lockin at least a first and a second locking position, wherein said lockingmember is adapted to, in said first locking position, lock an artificialcaput femur surface having at least one extending portion to a caputand/or collum femur, and wherein said locking member is adapted to, insaid second locking position, lock said artificial caput femur surfacetighter to the caput and/or collum femur.

In yet another embodiment, the locking member is adapted to lock in atleast a first and a second locking position, wherein the locking memberis adapted to; in the first locking position, lock an artificial caputfemur surface having at least one extending portion, to a first sizecaput and/or collum femur, and in said second locking position, locksaid artificial caput femur surface, to a second smaller size caputfemur and/or collum femur.

The hip joint has a caput femur integrated with a collum femur having acenter axis extending longitudinal along the collum and caput femur inthe center thereof. The collum femur is placed more distal than caputfemur. The medical device system comprises two or more medical devices,wherein each of the medical devices comprises an artificial caput femursurfaces being hollow, having a major opening adapted to be directeddistally, when said medical device is implanted. The artificial caputfemur surface is adapted to replace a caput femur hip joint surface,further having; a medical device caput center axis passing through saidmajor opening, being aligned with the caput femur center axis, when saidmedical device is implanted in a functional position in the hip joint.The medical device comprises a central part and a surrounding part, thecentral part being aligned with the medical device center axis and thesurrounding part surrounding the surface of the caput femur notincluding the central part. The medical device further comprises; aninner surface adapted to have a first distal distance extendingperpendicularly from said medical device caput center axis to said innersurface of the surrounding part of said artificial caput femur surface.The first distal distance is shorter than a second proximal distanceextending perpendicularly from the medical device caput center axis tosaid inner surface of said artificial caput femur surface, said secondproximal distance extending from a more proximal position on saidmedical device caput center axis than said first distal distance, beingthe second proximal distance, when said artificial caput femur surfaceis implanted in said functional position in the hip joint. The medicaldevice further comprising a locking member for implantation in a hipjoint of a patient. The locking member is adapted to assist in thefixation of said medical device to the collum and/or caput femur,wherein said locking member comprises an element adapted to lock saidartificial caput femur surface such that the caput femur remains claspedand restrained in said artificial caput femur surface, and at least oneof said artificial caput femur surfaces has a size adapted to replacethe caput femur hip joint surface of a corresponding size.

According to yet another embodiment, the medical device system furthercomprises two or more locking members. The two locking members havedifferent sizes when in their locking position, and thus being adaptedto lock different artificial caput femur surfaces of different sizes toa caput femur, or an artificial caput femur surfaces to caput femur ofdifferent sizes, such that the caput femur remains clasped andrestrained in the artificial caput femur surface, when locked by one ofthe two or more locking members having the matching size.

According to another embodiment, the locking member is adapted to lockin at least a first and a second locking position. The locking member isadapted to; in said first locking position, lock a first artificialcaput femur surface having at least one extending portion to a firstsize caput femur and/or collum femur, and in said second lockingposition, lock a second artificial caput femur surface having at leastone extending portion, to a second smaller size caput and/or collumfemur.

According to yet another embodiment the locking member is adapted tolock in at least a first and a second locking position. The lockingmember is adapted to, in said first locking position, lock an artificialcaput femur surface having at least one extending portion to a caputand/or collum femur, and wherein said locking member is adapted to, insaid second locking position, lock said artificial caput femur surfacetighter to the caput and/or collum femur.

According to another embodiment, the locking member is adapted to lockin at least a first and a second locking position, wherein said lockingmember is adapted to; in said first locking position, lock an artificialcaput femur surface having at least one extending portion, to a firstsize caput and/or collum femur, and in said second locking position,lock said artificial caput femur surface, to a second smaller size caputfemur and/or collum femur.

In one embodiment the locking member comprises a loop-shaped elementadapted to be connected in situ for creating said loop shape surroundingthe caput and/or collum femur, when implanted.

According to yet another embodiment, a loop shaped element is adapted tohave a first locking state, in which said loop shape has a first innercircumference, and wherein said loop shaped element is further adaptedto have a second locking state, in which said loop shaped element has asecond smaller inner circumference.

The medical device system could according to another embodiment have aloop shaped element adapted to further have a third locking state, inwhich said loop shape has a third inner circumference being smaller thansaid first and second inner circumference.

In yet another embodiment, the locking member is further adapted to bearranged in an area extending a distance beyond the maximum diameter ofthe caput femur.

The loop shaped element could in any of the embodiments herein be anelement selected from: a cord, a wire and a band.

In yet another embodiment, the locking member could comprise a first andsecond engagement member. The first engagement member could be adaptedto engage the second engagement member, when implanted.

In yet another embodiment, the first and second engagement members areadapted to mechanically self connect by introducing a male part of saidfirst engagement member into a female part of said second engagementmember.

In yet another embodiment of the medical device system, the first andsecond engagement members are fixated to the artificial caput femursurface on the inside thereof.

The first and second engagement members could according to anotherembodiment be fixated to the artificial caput femur surface on theoutside thereof.

According to yet another embodiment, the artificial caput femur surfacecould comprise at least one slit, and the first and second engagementmembers could be fixated to the artificial hollow caput femur surface ontwo different sides of a slit, respectively.

According to other embodiments the first and second engagement memberscould be fixated to the artificial hollow caput femur surface, onextending portion thereof.

The loop shaped element could comprise a first and second end, and thefirst and second end could be adapted to be connected to form the loopshaped element using an engagement member comprising two pivotablelocking parts.

According to another embodiment, the first locking part is pivotablyattached both to the first end of the locking member and to the secondlocking part.

In yet other embodiments the second locking part could be attached tothe first locking part in a point arranged substantially in the middleof said first locking part.

In yet other embodiments, the first and second locking member ends arecould be arranged overlapping each other when locked together.

According to yet another embodiment, the locking member could be adaptedto be fixated to the artificial caput femur surface, perpendicularly tothe center axis of the caput and collum femur and adapted to partiallysurround the caput and/or collum femur and clasp the caput and/or collumfemur.

In yet other embodiments the locking member could be made from anelastic material, for enabling the locking member to be placed onto theartificial caput femur surface, clasping the caput and/or collum femur.

The locking member could comprise a first and second portion, the firstand second portions could be pivotably connected at a hinge. Wherein thefirst and second portions could be adapted to pivot for enabling thelocking member to be placed partially surrounding the artificial caputfemur.

In yet other embodiments the locking member could further comprise alocking element adapted to lock the connection between the first andsecond portion, such that the locking member can be locked clasping thecaput and/or collum femur, when implanted.

In some embodiments disclosed herein the locking member comprises atleast one mechanical fixating member adapted to be placed in contactwith the artificial caput femur surface, and in the bone of the collumand/or caput femur, thereby fixating the artificial caput femur surfaceto the collum and/or caput femur.

According to yet another embodiment, the at least one mechanicalfixating member is adapted to travel from one point on the artificialcaput femur surface, through a portion of the bone of the collum and/orcaput femur, and to a second point on the artificial caput femursurface.

According to yet another embodiment, the length of the mechanicalfixating member is changeable, and wherein said mechanical fixatingmember thus can be shortened for squeezing and further fixating theartificial caput femur surface to the collum and/or caput femur.

The mechanical fixating member could according to one embodimentcomprise a threaded portion.

The mechanical fixating member could according to another embodiment beadapted to be placed in contact with the artificial caput femur surfaceat the extending portion thereof.

A medical device system for implantation in a hip joint of a patient isfurther provided. The hip joint has a caput femur integrated with acollum femur having a center axis extending longitudinal along thecollum and caput femur in the center thereof. The medical device systemcould comprise an artificial hollow caput femur surface comprising atleast one extending portion adapted to clasp a portion of the caputand/or collum femur, and a locking member adapted to assist in thefixation of the medical device to a portion of the caput and/or collumfemur. The locking member could comprise an element adapted to lock theartificial caput femur surface such that the caput femur remains claspedand restrained in said artificial caput femur surface.

In yet another embodiment, the hollow artificial caput femur surface isadapted to at least partly cover the caput femur, when implanted in afunctional position in the hip joint.

In yet another embodiment, the artificial caput femur surface could beadapted to be placed in an acetabulum bowl, or an artificial replacementtherefore, when implanted in the functional position in the hip joint.

The artificial caput femur surface could in other embodiments be adaptedto have a changeable first distal distance, thus being adapted to bemounted onto the caput femur, when implanted in the hip joint.

In other embodiments, the artificial caput femur surface could beadapted to have the maximum second proximal distance, extendingperpendicularly from said medical device caput center axis to said innersurface of said artificial caput femur surface, wherein said maximumsecond proximal distance is located on a part of said medical devicecaput center axis located more proximal than said major opening, whensaid artificial caput femur surface is mounted in said functionalposition in the hip joint. The artificial caput femur surface couldfurther be adapted to have the closest first distal distance extendingperpendicularly from said medical device caput center axis to said innersurface of said artificial caput femur surface, being smaller than themaximum second proximal distance. The maximum second proximal distancecould be extending from the medical device caput center axis, moreproximal than the closest first distal distance, when implanted in saidfunctional position in the hip joint.

According to yet another embodiment, the medical device could furthercomprise at least one slit in said artificial caput femur surfaceallowing said device to vary the diameter of a major opening, thusallowing the device to be mounted on said caput femur. The artificialcaput femur surface could comprise a major opening having at leastpartly, a diameter or cross sectional distance adapted to be changed inat least one of the following ways: increase to be able to mount saidmedical device on the caput femur, decrease to mechanically fixate andenable a stable position of said medical device on the caput femur whenmounted thereon.

The closest distance from the inner surface of said first extendingportion to said caput and collum femur center axis, perpendicular tosaid caput and collum femur center axis could be adapted to beadjustable by said extending portion comprising at least one of theelements selected from a list consisting of: an elastic portion, abendable portion, a flexible portion, a compressible portion, and amovable portion.

According to yet another embodiment, the closest distance from the innersurface of the first extending portion to the caput and collum femurcenter axis, perpendicular to said caput and collum center axis, isadapted to be adjusted by said locking member.

In yet another embodiment, the medical device could comprise at leasttwo parts adapted to be connected to each other during a surgical orarthroscopic/laparoscopic procedure.

The artificial caput femur surface could in some embodiments beincomplete in its surface distribution.

The artificial caput femur surface could in other embodiments be adaptedto be fixated to the caput femur without penetration of the cortex ofcaput femur or the femur bone.

In yet other embodiments, the medical device could be adapted to befixated by means of an elastic member exerting a squeezing force on thecaput femur.

In yet other embodiments of the medical device, the elastic member couldbe adapted to exert a squeezing force on the caput femur is the saidlocking member.

According to other embodiments, the locking member could be adapted tolock in at least a first and a second locking position, and the lockingmember could be adapted to; in the first locking position, lock a firstartificial caput femur surface having at least one extending portion, toa first size caput femur and/or collum femur, and in the second lockingposition, lock a second artificial caput femur surface having at leastone extending portion, to a second smaller size caput and/or collumfemur.

In yet other embodiments the locking member could be adapted to lock inat least a first and a second locking position, and the locking membercould be adapted to, in said first locking position, lock an artificialcaput femur surface having at least one extending portion to a caputand/or collum femur. The locking member could further be adapted to, insaid second locking position, lock said artificial caput femur surfacetighter to the caput and/or collum femur.

In yet other embodiments the locking member could be adapted to lock inat least a first and a second locking position, wherein said lockingmember is adapted to; in said first locking position, lock an artificialcaput femur surface having at least one extending portion, to a firstsize caput and/or collum femur, and in said second locking position,lock said artificial caput femur surface, to a second smaller size caputfemur and/or collum femur.

In yet other embodiments the locking member comprises a loop-shapedelement adapted to be connected in situ for creating said loop shapesurrounding the caput and/or collum femur, when implanted.

The loop shaped element could be adapted to have a first locking state,in which said loop shape has a first inner circumference, wherein saidloop shaped element is further adapted to have a second locking state,in which said loop shaped element has a second smaller innercircumference.

The loop shaped element could be adapted to further have a third lockingstate, in which said loop shape has a third inner circumference beingsmaller than said first and second inner circumference. The lockingmember could further be adapted to be arranged in an area extending adistance beyond the maximum diameter of the caput femur.

In other embodiments, the loop shaped element could be an elementselected from: a cord, a wire and a band.

The locking member according to any one of the embodiments couldcomprise a first and second engagement member, and wherein said firstengagement member is adapted to engage said second engagement member,when implanted. The first and second engagement members could be adaptedto mechanically self connect by introducing a male part of said firstengagement member into a female part of said second engagement member.

According to another embodiment, the first and second engagement memberscould be fixated to the artificial caput femur surface on the insidethereof.

In yet other embodiments, the first and second engagement members arefixated to the artificial caput femur surface on the outside thereof.

In yet other embodiments the artificial caput femur surface couldcomprise at least one slit, wherein said first and second engagementmember could be fixated to the artificial hollow caput femur surface ontwo different sides of the slit, respectively.

The first and second engagement members could be fixated to theartificial hollow caput femur surface, on extending portion thereof.

According to other embodiments, the loop shaped element could comprise afirst and second end, wherein said first and second ends could beadapted to be connected to form the loop shaped element using anengagement member comprising two pivotable locking parts.

In yet other embodiments, the first locking part is pivotably attachedboth to the first end of the locking member and to said the secondlocking part.

In other embodiments, the locking part could be attached to the firstlocking part in a point arranged substantially in the middle of saidfirst locking part.

The first and second locking member ends could be arranged overlappingeach other when locked together.

In other embodiments a locking member could be adapted to be fixated tothe artificial caput femur surface, perpendicularly to said center axisof the caput and collum femur and adapted to partially surround thecaput and/or collum femur and clasp the caput and/or collum femur.

In some embodiments, the locking member is made from an elasticmaterial, for enabling the locking member to be placed onto theartificial caput femur surface, clasping the caput and/or collum femur.

The locking member could comprise a first and second portion, and thefirst and second portion could be pivotably connected at a hinge, andwherein said first and second portions are adapted to pivot for enablingthe locking member to be placed partially surrounding the artificialcaput femur.

In yet other embodiments the locking member could further comprise alocking element adapted to lock the connection between said first andsecond portion, such that said locking member can be locked clasping thecaput and/or collum femur, when implanted.

The locking member could comprise at least one mechanical fixatingmember adapted to be placed in contact with the artificial caput femursurface, and in the bone of the collum and/or caput femur, therebyfixating the artificial caput femur surface to the collum and/or caputfemur.

In yet other embodiments, the at least one mechanical fixating membercould be adapted to travel from one point on the artificial caput femursurface, through a portion of the bone of the collum and/or caput femur,and to a second point on the artificial caput femur surface.

The length of the mechanical fixating member could be adapted to bechangeable, such that the mechanical fixating member can be shortenedfor squeezing and further fixating the artificial caput femur surface tothe collum and/or caput femur.

A locking member system comprising two or more locking members accordingto any one of the embodiments herein is further provided. The twolocking members have different sizes, when in their locking position.The locking members could be adapted to lock an artificial caput femursurface of a corresponding size, selected from different sizes thereof.

The locking member could comprise an artificial caput femur surfacesurface, comprising an extending portion, wherein said at least oneextending portion is constructed according to at least one of thefollowing alternatives; a) circumferentially extends discontinuouslyalong said equator line and b) extends with different distal extensionin different extending portions or part of such portion of saidcircumferential extension.

The locking member could comprise a lock holding member to hold saidlocking member in position onto said extending portion of the artificialcaput femur surface.

The locking member could be integrated in the bearing surface of theartificial caput femur surface to hold said locking member in positiononto said extending portion of the artificial caput femur surface.

The hip joint has a collum femur, having a first axial distributionleading to a caput femur, wherein said collum femur is placed distal tothe caput femur, a center axis of the collum and caput femur in linewith the first axial distribution being the caput femur center axis,wherein the caput femur has a substantially ball shaped configurationwith an outer maximum radius perpendicular to the caput femur centeraxis, the caput femur being placed in a bowl shaped acetabulum, havingan opening, wherein the bowl shaped acetabulum has a second axialdistribution with an acetabulum center axis from the center of thebottom of the acetabulum bowl and following the center of the bowltowards the center of the opening of the bowl, towards the caput femur,wherein the acetabulum bowl has an inner maximum radius perpendicular tothe acetabulum center axis, wherein the caput femur center axis is inline/aligned with the acetabulum center axis, in a special centeredposition, when the caput femur is placed; aligned, centered andsymmetrical in the acetabulum bowl in the hip joint, the aligned centeraxis is defined as the hip joint center axis, wherein the caput femurand the acetabulum has one hip joint surface each, placed towards andcontacting each other, wherein the hip joint surfaces carrying weight inthe hip joint are the weight carrying surfaces, wherein the outermaximum radius of the caput femur is forming a circular extending,maximum caput femur radius circle, extending perpendicular to the hipjoint center axis, defining a maximum caput femur radius cross-sectionperpendicular to the hip joint center axis, wherein: said medical devicecomprises at least one artificial hip joint surface, adapted to at leastpartly replace at least one of the hip joint surfaces, said artificialhip joint surface at least partly being hollow and having an inner andouter surface, wherein said artificial hip joint surface has anartificial hip joint surface center axis aligned with the hip jointcenter axis when the hip joint is placed in the special centeredposition, when at least one of said artificial hip joint surfaces isimplanted in the hip joint, with the caput femur or an artificial caputfemur surface placed; aligned, centered and symmetrical in theacetabulum bowl or an artificial acetabulum surface in the hip joint,wherein said medical device comprises a central part and a surroundingpart, the central part being aligned with the artificial hip jointsurface center axis and the surrounding part surrounding the surface ofthe caput femur or an artificial caput femur surface not including thecentral part, wherein the caput femur or an artificial caput femursurface, has a maximum caput femur radius cross-section, in which theouter maximum radius of the caput femur or said artificial caput femursurface is forming a circular extending maximum caput femur orartificial caput femur radius circle, extending perpendicular to the hipjoint center axis, defining the maximum caput femur radius cross-sectionperpendicular to the hip joint center axis or perpendicular to saidartificial hip joint surface center axis, when the hip joint is placedin said special centered position, wherein the surrounding part of saidat least one artificial hip joint surface comprises at least one firstextending portion of the artificial hip joint surface for extending indistal direction at least partly beyond the maximum caput femur radiuscross-section, when the hip joint is placed in said special centeredposition, when at least one of the artificial hip joint surfaces isimplanted in the hip joint, wherein said at least one first beyond partis adapted to have a closest perpendicular distance to said artificialhip joint surface center axis, being smaller than an inner maximumdistance, extending perpendicularly from said artificial hip jointsurface center axis to said inner surface of said artificial hip jointsurface, when the hip joint is placed in the above mentioned specialcentered position and said artificial hip joint surface is placed in afunctional position in the hip joint, thus adapted to create andcreating a more stable position of said artificial hip joint surfacewhen mounted in the hip joint.

The hip joint has a

caput femur hip joint surface partly being the contacting surface of thehip joint, the

hip joint further having a collum femur, having a first axialdistribution leading to a

caput femur, wherein a center axis of the first axial distribution ofthe the collum

femur and the caput femur, being the caput femur center axis, whereinthe collum

femur is placed more distal than caput femur, wherein;

-   -   said medical device comprises an artificial caput femur surface        being hollow,

having a major opening adapted to be directed towards the caput femur ora

surgically modified caput femur, wherein said artificial caput femursurface is

adapted to replace a caput femur hip joint surface, wherein saidartificial caput

femur surface further having;

-   -   a medical device caput center axis passing through said major        opening,

being aligned with the caput femur center axis, when said medical deviceis

implanted in a functional position in the hip joint, wherein saidmedical

device comprises a central part and a surrounding part, the central part

being aligned with the medical device center axis and the surroundingpart

surrounding the surface of the caput femur or the surgically modifiedcaput

femur not including the central part, and wherein said medical device

further comprising

-   -   an inner surface adapted to have a first distal distance        extending

perpendicularly from said medical device caput center axis to said inner

surface of the surrounding part of said artificial caput femur surface,said

first distal distance being shorter than a second proximal distance

extending perpendicularly from said medical device caput center axis to

said inner surface of said artificial caput femur surface, said second

proximal distance extending from a more proximal position on said

medical device caput center axis than said first distal distance, beingthe second proximal distance, when said artificial caput femur surfaceis

implanted in said functional position in the hip joint.

6. The medical device for implantation in a hip joint of a patientaccording to any of the preceding claims, the hip joint having

an acetabulum, being a bowl shaped contacting surface of the hip jointcomprising

a substantially circular major opening in distal direction of theacetabulum in the

hip joint and a bottom center point in said bowl shaped acetabulumproximally in

the hip joint, wherein an acetabulum center axis extends from the bottompoint

through the center point of the substantially circular opening, whereinthe

acetabulum has a weight carrying surface contacting a ball shaped caputfemur

located in the acetabulum bowl in the hip joint, wherein the caput femuris

connected to the collum femur, and the collum femur has a center axisaligned

with a caput femur center axis, wherein;

-   -   said medical device comprises an artificial acetabulum surface        adapted to

replace the weight carrying surface of the acetabulum, wherein saidartificial

acetabulum surface is hollow and has a major acetabulum opening adaptedto

be directed towards the caput femur or an artificial replacement of atleast the surface of the caput femur, wherein said artificial acetabulumsurface is adapted to receive a caput femur or an artificial replacementof at least the surface of the caput femur, in said hollow artificialacetabulum surface, when implanted in the hip joint, said artificialacetabulum surface having; a medical device acetabulum center axis,adapted to be aligned with the acetabulum center axis, when saidartificial acetabulum surface is placed in the hip joint, and an innersurface adapted to have a first distal distance extendingperpendicularly from said medical device acetabulum center axis, to saidinner surface of said artificial acetabulum surface, said first distaldistance being shorter than a second proximal distance extendingperpendicularly from said medical device acetabulum center axis to saidinner surface of said artificial acetabulum surface, said secondproximal distance extending from a more proximal position on saidmedical device acetabulum center axis than said first distal distance,when said artificial acetabulum surface is implanted functionally in thehip joint, wherein said artificial acetabulum surface is adapted toreceive in the hollow artificial acetabulum surface the caput femur oran artificial replacement of at least the surface of the caput femur,when implanted in the hip joint, for achieving a functional hip joint.

Method

A method for implantation of a locking member in a hip joint of apatient is further provided, the hip joint having a caput femurintegrated with a collum femur having a center axis extendinglongitudinal along the collum and caput femur in the center thereof, themethod comprise the following steps;

-   -   performing an operation in a hip joint surgically or        arthroscopically,    -   placing an artificial hollow caput femur surface mounted onto        caput femur,    -   placing a locking member for assisting in the fixation of the        artificial caput femur surface, wherein said artificial caput        femur surface comprises at least one extending portion adapted        to clasp a portion of the caput and/or collum femur,    -   clasping with the least one extending portion a portion of the        caput and/or collum femur,

and wherein said locking member comprises an element adapted to locksaid artificial caput femur surface such that the caput femur remainsclasped and restrained in said artificial caput femur surface,

-   -   locking by said locking member element said artificial caput        femur surface such that the caput femur is    -   remaining clasped and restrained in said artificial caput femur        surface.

The method comprising the steps of;—locking in said first lockingposition, and—locking in second position locking tighter the artificialcaput femur surface with at least one extending portion, to the caputand/or collum femur.

According to another embodiment, the locking member is adapted to lockin at least a first and a second locking position, the method comprisingthe steps of;—locking in said first locking position a first artificialhollow caput femur surface, and—locking in second position a secondsmaller artificial caput femur surface with at least one extendingportion, to the caput and/or collum femur.

The method using a locking member according to any one of the precedingembodiments, wherein said locking member comprises a loop-shapedelement, the method comprise the step of; locking in situ said loopshape surrounding the caput and/or collum femur.

The method according to any of the embodiments, locking said loop shapedelement in a first locking state, in which said loop shape has a firstinner circumference, and locking said loop shaped element in a secondlocking state, in which said loop shaped element has a second smallerinner circumference.

The method using the locking member according to any of the embodiments,wherein said locking member further comprises a medical devicecomprising, an artificial caput femur surface being hollow, having amajor opening adapted to be directed distally and being adapted toreplace a caput femur hip joint surface, wherein said artificial caputfemur surface further having;

a medical device caput center axis passing through said major opening,being aligned with the caput and collum femur center axis, when saidmedical device is implanted in a functional position in the hip joint,wherein said medical device comprises a central part and a surroundingpart, the central part being aligned with the medical device center axisand the surrounding part surrounding the surface of the caput femur notincluding the central part, and wherein said medical device furthercomprises; an inner surface adapted to have a first distal distanceextending perpendicularly from said medical device caput center axis tosaid inner surface of said surrounding part of said artificial caputfemur surface, said first distal distance being shorter than a secondproximal distance extending perpendicularly from said medical devicecaput center axis to said inner surface of said artificial caput femursurface, said second proximal distance extending from a more proximalposition on said medical device caput center axis than said first distaldistance, being the second proximal distance, when said artificial caputfemur surface is implanted in said functional position in the hip joint,the artificial caput femur surface comprise a lock holding member forholding the locking member in its position, the method involves the stepof;

-   -   placing the artificial caput femur surface onto caput femur        during a surgical or arthroscopical operation,—placing the        locking member and—locking said artificial caput femur surface        to caput femur,—holding said locking member in place by said        lock holding member.

A method for implantation at least one medical device in a hip joint ofa patient, the hip joint having a caput femur integrated with a collumfemur having a center axis extending longitudinal along the collum andcaput femur in the center thereof, wherein the collum femur is placedmore distal than caput femur, wherein;

-   -   said medical device system comprises two or more medical        devices, wherein each of the medical devices comprising:

an artificial caput femur surfaces being hollow, having a major openingadapted to be directed distally, when said medical device is implanted,wherein said artificial caput femur surface is adapted to replace acaput femur hip joint surface, further having;

a medical device caput center axis passing through said major opening,being aligned with the caput femur center axis, when said medical deviceis implanted in a functional position in the hip joint, wherein saidmedical device comprises a central part and a surrounding part, thecentral part being aligned with the medical device center axis and thesurrounding part surrounding the surface of the caput femur notincluding the central part, and wherein said medical device furthercomprises;

an inner surface adapted to have a first distal distance extendingperpendicularly from said medical device caput center axis to said innersurface of the surrounding part of said artificial caput femur surface,said first distal distance being shorter than a second proximal distanceextending perpendicularly from said medical device caput center axis tosaid inner surface of said artificial caput femur surface, said secondproximal distance extending from a more proximal position on saidmedical device caput center axis than said first distal distance, beingthe second proximal distance, when said artificial caput femur surfaceis implanted in said functional position in the hip joint, and a lockingmember for implantation in a hip joint of a patient, wherein saidlocking member is adapted to assist in the fixation of said medicaldevice to the collum and/or caput femur, wherein said locking membercomprises an element adapted to lock said artificial caput femur surfacesuch that the caput femur remains clasped and restrained in saidartificial caput femur surface, wherein at least one of said artificialcaput femur surfaces has a size adapted to replace the caput femur hipjoint surface of a corresponding size, wherein the method includes thestep of; surgically or arthroscopically implanting two or moreartificial caput femur surfaces to find the right size to lock onto thecaput femur.

The method according to any of the embodiments further comprising two ormore locking members, wherein the two locking members have differentsizes, when in their locking position, and thus being adapted to lockdifferent artificial caput femur surfaces of different sizes to a caputfemur, or an artificial caput femur surfaces to caput femurs ofdifferent sizes, such that the caput femur remains clasped andrestrained in the artificial caput femur surface, when locked by one ofthe two or more locking members having the matching size, the methodinvolves the step of; using two or more locking members to lock theartificial caput femur surface of the correct size to the caput femur.

According to one embodiment, the at least one extending portion ismounted according to at least one of the following alternatives:

a) extending circumferentially discontinuously along said equator linehaving enough circumferential distance lacking any extending portion andb) extending with different distal extension in different extendingportions or part of such portion of said circumferential extension.

Please note that any embodiment or part of embodiment, feature, method,associated system, part of system described herein or in the associatedfigures may be combined in any way.

BRIEF DESCRIPTION OF DRAWINGS

The invention is now described, by way of example, with reference to theaccompanying drawings, in which:

FIG. 1 shows the hip joint of a human patient in section,

FIG. 2 shows the pelvis in a frontal view,

FIG. 3 shows the placing of an artificial caput femur surface on thecaput femur in conventional surgery,

FIG. 4 shows a medical device for implantation in a hip joint of apatient,

FIG. 5 shows the medical device according to one embodiment,

FIG. 6 shows the medical device according to another embodiment,

FIG. 7 shows an artificial caput femur surface in section having a majoropening adapted to travel over and beyond the maximum diameter of thecaput femur,

FIG. 8a shows an artificial caput femur surface 45 according to a firstembodiment,

FIG. 8b shows the artificial caput femur surface when fixated to thecaput femur,

FIG. 8c shows the hip joint is section when a medical device isimplanted,

FIG. 9 shows an artificial acetabulum surface according to a firstembodiment,

FIG. 10a-c shows an artificial acetabulum surface according to a secondembodiment,

FIG. 11a discloses the adjustable locking member to be mounted on theartificial acetabulum surface,

FIG. 11b-11e shows different embodiments of a locking member and anengagement member,

FIG. 12a shows a medical device and a locking member according to yetanother embodiment,

FIG. 12b shows a medical device and a locking member according to yetanother embodiment,

FIG. 13a shows a medical device with an integrated locking memberaccording to one embodiment,

FIG. 13b shows a medical device with an integrated locking memberaccording to another embodiment,

FIG. 14 shows an embodiment of a medical device and a mechanicalfixating member,

FIG. 15 shows a first kit comprising three artificial caput femursurfaces and one locking member,

FIG. 16 shows a second kit comprising one artificial caput femursurfaces and three locking members,

FIG. 17 shows a third kit comprising three artificial caput femursurfaces and three locking members.

DETAILED DESCRIPTION

The hip joint is a synovial ball and socket joint which permits a largemotion range for allowing a plurality of different movements of thelower limb. From a neutral position the following movements of the hipjoint are normally possible: Lateral or external rotation, 30° with thehip extended, 50° with the hip flexed, medial or internal rotation 40°,extension or retroversion 20°, flexion or anteversion 140°, abduction50° with hip extended, 80° with hip flexed, adduction 30° with hipextended, 20° with hip flexed.

When replacing the natural hip joint with an artificial, the depth ofthe artificial acetabulum will affect the motion range of the hip joint,the deeper the acetabulum bowl is made the more restrictive it is to themotion range. A deeper bowl has the advantage of reducing the risk ofhip joint luxation, the risk of which is a major drawback withprosthetic hips of today.

The caput and collum femur are to be understood as the proximal portionof the femoral bone. In orthopedic surgery the caput and/or collum femuris sometimes surgically modified, e.g. bone is removed to adapt theproximal portion of the femoral bone to a particular prosthesis. For thepurpose of this application the caput/collum femur are to be understoodas either the natural caput/collum femur or a surgically modifiedcaput/collum femur.

The anatomy of the hip joint and its surroundings is further disclosedin: Marieb et al., Human Anatomy, 2003, Benjamin Cummings, SanFrancisco, pages 195-202 and in Moore et al., Clinically orientedanatomy, 1999, Lippincott, Williams & Wilkins, Baltimore, pages 501-653,both hereby incorporated by reference.

Centrally in the body should herein be understood as a point ofreference located at the intersection of the Median plane and theCoronal plane and in the center part of the heart along a longitudinalaxis (Caudal-Cranial). Proximal and distal are direction or locationterms used in relation to said point centrally in the body and hence adistal point is a point farther away from the central point in relationa proximal point of the same structure. Other anatomical terms usedherein are further described in Moore et al., Clinically orientedanatomy, 1999, Lippincott, Williams & Wilkins, Baltimore, pages 2-10,which is hereby incorporated by reference.

Functional hip movements are to be understood as movements of the hipthat at least partly correspond to the natural movements of the hip. Onsome occasions the natural movements of the hip joint might be somewhatlimited or altered after hip joint surgery, which makes the functionalhip movements of a hip joint with artificial surfaces somewhat differentthan the functional hip movements of a natural hip joint.

Everyday activities is to be understood as activities which are notconnected to any extreme movements, such that some physical sportsrequire. For example, everyday activities comprise: walking, sitting,cycling etc.

The functional position of an implantable medical device or prosthesisis the position in which the hip joint can perform functional hipmovements. The final position is to be understood as a functionalposition in which the medical device needs no further position change.

Elasticity is to be understood as a materials ability to deform in anelastic way.

Elastic deformation is when a material deforms under stress (e.g.external forces), but returns to its original shape when the stress isremoved. A more elastic material is to be understood as a materialhaving a lower modulus of elasticity. The elastic modulus of an objectis defined as the slope of its stress-strain curve in the elasticdeformation region. The elastic modulus is calculated as stress/strain,where stress is the force causing the deformation, divided by the areato which the force is applied; and strain is the ratio of the changecaused by the stress.

Stiffness is to be understood as the resistance of an elastic body todeformation by an applied force.

Biocompatible material is to be understood as being a material with lowlevel of immune response. Biocompatible materials are sometimes alsoreferred to as biomaterials. Analogous is biocompatible metals abiocompatible metal with low immune response such as titanium ortantalum. The biocompatible metal could also be a biocompatible alloycomprising at least one biocompatible metal.

Form fitting is to be understood as an element having a part or sectionwhich is adapted to enable a mechanical connection of said element to atleast one other element using said part or section. Form fittedstructure is a structure of an element which enables form fitting.

In the following a detailed description of embodiments of the presentinvention will be given. In the drawing figures, like reference numeralsdesignate identical or corresponding elements throughout the severalfigures. It will be appreciated that these figures are for illustrationonly and are not in any way restricting the scope of the invention.Thus, any references to direction, such as “up” or “down”, are onlyreferring to the directions shown in the figures. Also, any dimensionsetc. shown in the figures are for illustration purposes.

FIG. 1 shows the hip joint of a human patient in section. The hip jointcomprises a caput femur 5 placed at the very top of collum femur 6 whichis the top part of the femoral bone 7. The caput femur is in connectionwith the acetabulum 8 which is a bowl shaped part of the pelvic bone 9.Both the caput femur surface 10 and the acetabulum surface 11 arecovered with articular cartilage 13 which acts as a cushion in the hipjoint. In patients with hip joint osteoarthritis, this articularcartilage 13 is abnormally worn down due to a low grade inflammation.The hip joint is surrounded by the hip joint capsule 12 which providessupport for the joint and hinders luxation. After conventional hip jointsurgery, penetrating the hip joint capsule 12, the capsule 12 isdramatically weakened due to the limited healing possibilities of itsligament tissue. By performing hip joint surgery without damaging thehip joint capsule 12 the patient can fully recover and place equalamount of strain on an artificial joint as is possible on a natural one.

FIG. 2 shows the pelvis in a frontal view. Pelvis comprises the rightand left hip bone making up the pelvic bone, in turn comprising theSacrum 1803, Ilium 1802, Pubis 1804 and Ischium 1801. The hip jointhouses the right and left acetabulum 8 a,b placed laterally and distallyin the pelvis. The acetabulum 8 a,b being a spherically shaped cavity inthe hip bones making up one of the parts of the hip joint, theacetabulum 8 a,b being adapted to house the caput femur 5, being theproximal portion of the femoral bone 7 having a spherical contactingsurface adapted to be placed in the acetabulum 8 a,b and thus creatingthe operable hip joint. The pelvis has a lateral-medial axis X extendingsubstantially from the bottom of the left acetabulum 8 a to the bottomof the right acetabulum 8 b, the pelvis further having a proximal-distalY axis extending perpendicular to said lateral-medial axis, centrallyand substantially along the length of the patient, passing the dorsalportions of the pubic symphysis 1805 and substantially following thespinal cord 1806, intersecting the lateral-medial axis X.

FIG. 3 shows the placing of an artificial caput femur surface 45 on thecaput femur in conventional surgery. The artificial caput femuraccording to this embodiment comprises slits 49 and arms 50 making thestructure of the artificial caput femur surface flexible for claspingthe caput femur 5 and going beyond the maximum diameter of the caputfemur 5. Furthermore the artificial caput femur surface 45 can beinserted into a hip joint through a hole smaller than the fullfunctional size of the artificial caput femur surface 45, enabling aless invasive surgical procedure.

FIG. 4 shows a medical device for implantation in a hip joint of apatient. The medical device comprises an artificial caput femur surface45 being hollow, having a major opening 1507 adapted to be directedtowards the caput femur or a surgically modified caput femur whenimplanted in the hip joint. A medical device caput center axis 1504passes through the major opening 1507, when said medical device isimplanted in a functional position in the hip joint. The medical devicecomprises an inner surface adapted to have a first distal distance 1503extending perpendicularly from said medical device caput center axis1504 to said inner surface of said artificial caput femur surface 45.The first distal distance 1503 being shorter than a second proximaldistance 1502 extending perpendicularly from said medical device caputcenter axis 1504 to said inner surface of said artificial caput femursurface 45. The second proximal distance 1502 extending from a moreproximal position on the medical device caput center axis 1504 than thefirst distal distance 1503, when the artificial caput femur surface 45is implanted in a functional position in the hip joint. The maximumfirst distal distance 1503 is located on a part of said medical devicecaput center axis 1504 substantially located more proximal than saidmajor opening 1507, when said artificial caput femur surface 45 ismounted in the functional position in the hip joint. The artificialcaput femur surface 45 is adapted to have a closest second proximal 1502distance extending perpendicularly from said medical device caput centeraxis 1504 to said inner surface of said artificial caput femur surface45, being smaller than the maximum first distal distance 1503. Themaximum first distal distance 1503 is extending from the medical devicecaput center axis 1504 more distal than the closest second proximaldistance 1502, when implanted in a functional position in the hip joint.

FIG. 5 shows the medical device according to one embodiment in which amaximum inner distance 1508 is extending from one or more predefinedpoints selected along a lengthwise extending part 1509 of the medicaldevice caput center axis 1504, in which said lengthwise extending part1509 is defined by two cross-sections 1510 a, 1510 b of said artificialcaput femur surface 45, extending perpendicular to the medical devicecaput center axis 1504, from both the distal 1511 a and proximal 1511 bend points of said part 1509 of the medical device caput center axis1504, in which both cross-sections 1510 a, 1510 b are placed at theouter limit 1512 a, 1512 b of the weight carrying surface 1513 of theartificial caput femur surface, in proximal P and distal D direction,respectively. The part 1509 of the medical device caput center axis 1504is placed between the cross-sections 1510 a, 1510 b.

FIG. 6 shows the medical device according to an embodiment where themedical device has a maximum outer distance 1514 extendingperpendicularly from a medical device caput center axis 1514 to theouter surface of the artificial caput femur surface. The artificialcaput femur surface 45 comprises at least one first beyond part 1516extending distally D, at least partly beyond a circular line 1517 of themaximum outer distance on the artificial caput femur surface 45, whenimplanted in said hip joint. The at least one first beyond part 1516 isadapted to have a closest distance 1518 from the inner surface of thefirst beyond part 1518 to the medical device caput center axis 1504,perpendicular to the medical device caput center axis 1504, beingsmaller than a maximum inner distance 1514 from the inner surface of theartificial caput femur surface 45 to the medical device caput centeraxis 1504, substantially perpendicular to the medical device caputcenter axis 1504. A maximum inner distance 1514 is extending from themedical device caput center axis 1504 substantially more proximal P thana major opening 1507. A lengthwise extending part of the medical devicecaput center axis 1504 is placed more proximal P than the major opening1507, when the artificial caput femur surface 45 is mounted in afunctional position in the hip joint. A circular line 1519 is definingthe major opening, which could further be defined as the smallestopening through which the caput femur can pass.

The area of the at least one first beyond part 1516 extending a distanceD beyond the maximum diameter of the caput femur 5, is here adapted tohold a locking member in place. The locking member could be a cord orwire, and can be placed around the artificial caput femur surface 45 forfurther fixation of the medical device. The band, cord or wire can bemechanically connected using a self locking member for forming aring-shaped element able to assist in the fixation of the artificialcaput femur surface 45 to the caput femur 5.

The distance D from the circular line 1517 of the maximum outer distanceon the artificial caput femur surface 45 to the circular line 1519 isdefining the major opening of the medical device. The distance D ischosen to extend to the circular line 1519 which have a closest distance1518 from the inner surface of the first beyond part 1518 to the medicaldevice caput center axis 1504. When the at least one first beyond part1516 is extending to the circular line 1519 the articulation or motionrange of the hip joint is not limited. According to the embodiment shownin FIG. 6, the distance D is approximately 5 mm, however in otherembodiments, the distance is approximately 10 mm.

FIG. 7 shows an artificial caput femur surface 45 in section having amajor opening 52 adapted to travel over and beyond the maximum diameterof the caput femur 5. The maximum diameter of the caput femur 5 isaccording to this embodiment positioned at a corresponding largestdiameter 61 of the artificial caput femur surface. A second distance 62is the distance that the artificial caput femur surface 45 travelsbeyond the maximum diameter of the caput femur 5. Said distance 62 isthe beyond part of the artificial caput femur surface 45 and is a partthat enabled the mechanical fixation of the artificial caput femursurface 45 to the caput femur 5, by said beyond part of the medicaldevice exerting a squeezing force of the caput femur 5 and/or collumfemur and clasps the caput femur 5.

FIG. 8a shows an artificial caput femur surface 45 according to oneembodiment in which the artificial caput femur surface 45 is adapted topass beyond the maximum diameter of the caput femur 5. This enables amechanical fixation using the form of said artificial caput femursurface 45. In this embodiment the artificial caput femur surface 45comprises at least one slit 49 adapted to make said artificial caputfemur surface 45 flexible for traveling over and beyond the maximumdiameter of the caput femur 5. It is also conceivable that theartificial caput femur surface 45 comprises two or more artificial caputfemur surface arms 50 which create a largest diameter 52. This largestdiameter 52 is according to one embodiment smaller the maximum diameterof the caput femur 5 enabling the mechanical fixation of the artificialcaput femur surface 45 by means of said artificial caput femur surfacearms 50. For further fixation, a locking member 59, which could be acord or wire 59, can be placed around the artificial caput femur surface45 beyond the maximum diameter of the caput femur 5. The band, cord orwire 59 can be mechanically connected using an engagement member 60 forforming a loop-shaped element able to assist in the fixation of theartificial caput femur surface 45 to the caput femur 5.

FIG. 8b shows the artificial caput femur surface 45 when fixated to thecaput femur 5 with the supporting band, cord or wire 59, as shown inFIG. 8a , placed around the artificial caput femur surface 45 beyond themaximum diameter of the caput femur 5. The arms 50 may also be adaptedto go into the bone of caput femur 5 to lock said artificial caput femursurface 45.

FIG. 8c shows the hip joint in section when a medical device has beenimplanted. The two extending portions 1823 a and 1823 b extendingdistally and clasping the spherical portion of the caput femur 5. Thehip joint has a caput femur 5 integrated with a collum femur 6 having acenter axis P extending longitudinal along the collum and caput femur inthe center thereof.

FIG. 9 shows an artificial caput femur surface 45 according to anembodiment in which the artificial caput femur surface comprisesmultiple movable portions 1224 connected to an interconnecting part 56by operable joints 1205 placed along one side of the movable portions1224. The artificial caput femur surface is further fixated to the caputfemur by a band, cord or wire 59 placed beyond the maximum diameter ofthe caput femur 5 at a distance D from the maximum diameter and the mostdistal end of the moveable partitions 1224 directed away from the joints1205. The artificial caput femur surface is fixated to the caput femurafter the movable portions 1224 have been placed in there functionalposition clasping the caput femur 5, and be movable during an operation.The section A-A shows a movable portion 1224 when not in its functionalstate. The movable portion 1224 being connected to an interconnectingpart 56 through a movable member in form of a hinge 1205 allowing themovable portion to move for being able to clasp the caput femur 5 and/orchanging the maximum diameter of the artificial caput femur surface forpassing through a hole smaller than the maximum diameter of the caputfemur surface in its functional state, in which case the movable memberis moved in a direction towards the center of the artificial caput femursurface (not shown).

FIG. 10a-c shows an artificial caput femur surface 45 according to anembodiment in which the artificial caput femur surface comprisesmultiple portions 46 connected to an interconnecting part 56 byfastening means 57, 58 placed along one side of the portions 56. Thefastening means comprises a first protruding portion 58 with an openingarranged on the one end of the portion 46. The opening in the firstprotruding portion 58 is adapted to interconnect with a secondprotruding portion 57 extending from a cut-out in the interconnectionpart 56. The multiple portions and the interconnection part can passthrough a hole smaller than the maximum diameter of the caput femursurface and can be assembled to clasp the caput femur 5 after beinginserted in the hip joint.

FIG. 11a discloses the adjustable locking member 59 to be mounted on theartificial caput femur surface 45. The locking member 59 is aloop-shaped element having two ends 59 a, 59 b adapted to bemechanically connected using an engagement member 60, thus forming aclosed loop with a certain circumference. The locking member 59 can bemade out of an elastic material which deforms under stress (e.g.external forces), but returns to its original shape when the stress isremoved.

The artificial caput femur surface 45 comprises two or more artificialcaput femur surface arms 50 which create a largest diameter 52. To lockthe artificial caput femur to the caput femur 5, the locking member 59is, when it is in an open state, pulled over the surface 45 until it atleast reaches an area extending a distance D beyond the maximum diameterof the caput femur 5. The locking member 59 can also be pulled until itreaches and rests on surface arms 50. When in its final position, thelocking member ends 59 a, 59 b are mechanically connected by theengagement member 60, and the artificial caput femur is held in place.

FIG. 11b-11e shows different embodiments of the locking member 59 andthe engagement member 60.

A first embodiment of a locking member 59 with engagement member 60 isdisclosed in FIG. 11b . The engagement member 60 comprises a first and asecond part 60 a, 60 b arranged in the first and second locking memberend 59 a, 59 b, respectively. The first and second engagement memberparts 60 a, 60 b have the shape of protrusions extending axially fromthe first and second locking member end, upwards and downwardrespectively. Thus forming a horizontally arranged gripping claw. Thefirst engagement member part 60 a has a cut-out in its lower surface andthe second engagement member part 60 b has a cut-out in its uppersurface. The cut-outs are so arranged that they form an upper and alower hook adapted to mechanically self connect by using the elasticityof the material and thus to form a loop with a certain circumferenceadapted to the diameter of the caput femur 5.

In a second embodiment of the locking member 59, shown in FIG. 11c , theengagement member 60′ is arranged in one first and second end 59 a, 59 bof the locking member. In the first locking member end 59 a one firstengagement member part 60 a′ in the form of a protrusion extendingradially, towards the center of the loop is arranged. The firstengagement member part 60 a is adapted to engage with one correspondingsecond engagement member part 60 b which is a protrusion arranged in theother second end 59 b of the locking member extending radially, from thecenter of the loop. The protrusions together are forming an engagementmember in the form of a vertically arranged gripping claw 60′. Thecircumference of the locking member can be adjusted by using more thanone second engagement member parts 60 b and arranging them at differentdistances from the second end 59 b of the locking member. In the secondembodiment in FIG. 11c there are more than one, preferably between threeand six, gripping claws 60 b′ arranged on the second end 59 b of thelocking member 59. The locking member 59 diameter can thus be adjusted.

A third embodiment of the locking member 59 is disclosed in FIG. 11d .In one first end 59 a of the locking member 59 there is a firstengagement member part 60 a″ in the form of a protrusion adapted to fitinto a corresponding second engagement member part 60 a″ in the form ofa recess or a hole in the other second end 59 b of the locking member59. It is also possible to have more than one hole so that thecircumference of the locking member 59 is adjustable.

A forth embodiment of the locking member 59 is disclosed in FIG. 11e .Here the first and second ends 59 a, 59 b of the locking member 59 areconnected by using an engagement member 60′″ comprising two pivotablefirst locking parts 60 a 1″′, 60 a 2′″ and one second locking part 60b′″. The first locking part 60 a 1′″ is pivotably attached both to thefirst end 59 a of the locking member 59 and to the second locking part60 a 2″′. The second locking part 60 a 2″′ is attached to the firstlocking part 60 a 1″′ in an engagement point arranged between the outerends of the first locking part 60 a 1′″, preferably in a point arrangedsubstantially in the middle of the first locking part 60 a 1″′. Thesecond locking part 60 a 2′″ is also adapted to engage with a protrudingpart 60 b′″ arranged in the second end 59 b of the locking member 59.When the second locking part 60 a 2″′ is engaged with the protrudingpart 60 b′″, the first and second end of the locking member 59 a, 59 bis locked together forming a closed loop with a first circumference. Thefirst and second locking member ends 59 a, 59 b can be pulled togetherforming a closed loop with a second circumference firmly enclosing theartificial caput femur and locking it to the caput femur 5. The firstand second locking member ends 59 a, 59 b are pulled together bypivoting the first locking part around its engagement point in the firstend 59 a of the locking member. The first and second locking member ends59 a, 59 b can be arranged either overlapping each other or beingarranged end to end when locked together, thus forming a loop with thesecond circumference.

FIG. 12a shows yet another embodiment of the locking member, in whichthe locking member does not encircle the caput femur surface 45completely, thus leaving a distance 2101 in which there is no lockingmember. According to the embodiment shown in FIG. 12a the locking member59 clamps the artificial caput femur surface by the locking member beingmade from an elastic material, such as stainless steel. The constructionwith locking member enables the artificial caput femur surface to bemade from a more resilient material, for allowing the artificial caputfemur surface to pass over the larger parts of the caput femur. Oneadvantage with the embodiment shown in FIG. 12 is that the lockingmember 59 does not have to be as elastic as the locking members thattotally encircles the caput femur, to still be mountable by the surgeonin situ.

FIG. 12b shows a locking member according to an embodiment similar tothe embodiment described previously, with reference to FIG. 12a .However, according to the embodiment shown in FIG. 12b , the lockingmember 59 comprises a hinge 2105 placed at the center of the lockingmember 59 to which two portions 2106 a, 2106 b of the locking member areconnected. In connection to the hinge a locking device is placedcomprising an male 2108 part adapted to connect to a female part 2109,thus creating a locking position. The locking member in the lockingposition clasps the artificial caput femur surface 45 and thus furtherfixates the artificial caput femur surface 45 to the caput femur. Theembodiment of FIG. 12b , with the hinge, enables the locking member tobe made from a less elastic material than is necessary in embodimentswhere the entire locking member is made from a single piece of material(such as the embodiment described with reference to FIG. 12a ). Theembodiment could further reduce the force needed to mount the lockingmember 59 onto the artificial caput femur 45 in situ.

FIG. 13a shows a locking member 59 according to yet another embodiment,in which the locking member 59 comprises a first and second unit 2102 a,2102 b placed at two sides of a slit 49 in the artificial caput femursurface 45. The first unit 2102 a comprises a male part 2103 which isinsertable into a female part 2104 of the second unit 2102 b, in whichit locks and thus places the slit 49 in a more closed state for fixatingthe artificial caput femur 45 surface to the caput femur.

FIG. 13b shows the medical device according to an embodiment in whichthe locking member 59 is placed centrally in the top of an embodiment ofthe artificial caput femur surface 45, in which the artificial caputfemur surface is dividable into two halves. The locking membercomprises, in accordance with the embodiment shown with reference toFIG. 13a , a first and second unit 2102 a, 2102 b, wherein said firstunit comprises a male part 2103 adapted to lock inside of a female parthoused in the second unit.

FIG. 14 shows an embodiment of the locking member 59 in which thelocking member 59 is adapted to travel from a first point of theartificial caput femur surface 45 through the bone of caput and/orcollum femur and to a second point of the artificial caput femur surface45. This embodiment could enable the locking member to fixate theartificial caput femur surface 45 to the caput femur by exerting asqueezing force and thus clamping the caput femur, and/or by the lockingmember 59 being inside the bone actually creating a mechanical lockthereby. According to the embodiment shown in FIG. 14 the locking member59 goes from one point of the artificial caput femur surface 45 toanother point on the artificial caput femur surface 45, through the boneof the caput/collum femur. However in other embodiments (not shown) thelocking member goes from a point of the artificial caput femur surfaceand into the bone of caput/collum femur, in these embodiments thelocking members could be mechanical fixating members, such as orthopedicscrews.

FIG. 15 shows a kit according to a first embodiment in which the kitcomprises three different sizes of artificial caput femur surfaces 45a,b,c, which could be chosen on the basis of the particular patient, ana locking member 59 with several states which thus could be tightenedaround the different artificial caput femur surfaces 45 a,b,c to fit theparticular patient.

FIG. 16 shows a kit according to a second embodiment in which the kitcomprises one artificial caput femur surface 45 and three differentsizes locking member 59 a,b,c which thus can be placed encircling theartificial caput femur surface 45 and be chosen for the particularfemoral bone of a particular patient.

FIG. 17 shows a kit according to a second embodiment in which the kitcomprises three different sizes of artificial caput femur surfaces 45a,b,c, which could be chosen on the basis of the particular patient, andthree different sizes of locking members 59 a,b,c which thus can beplaced encircling the artificial caput femur surface 45 and be chosenfor the particular femoral bone of a particular patient.

The kit solutions enables the orthopedic surgeon to choose a suitablemedical device when the caput femur is exposed, since determining theexact size and shape of the caput femur is very hard from merely imagescreated from outside of the body.

The medical device according to any of the embodiments could comprise atleast one material selected from a group consisting of:polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA) and fluorinatedethylene propylene (FEP). It is furthermore conceivable that thematerial comprises a metal alloy, such as cobalt-chromium-molybdenum ortitanium or stainless steel, or polyethylene, such as cross-linkedpolyethylene or gas sterilized polyethylene. The use of ceramic materialis also conceivable, in the contacting surfaces or the entire medicaldevice such as zirconium or zirconium dioxide ceramics or aluminaceramics. The part of the medical device in contact with human bone forfixation of the medical device to human bone could comprise a poorhousestructure which could be a porous micro or nano-structure adapted topromote the growth-in of human bone in the medical device for fixatingthe medical device. The porous structure could be achieved by applying ahydroxy-apatite (HA) coating, or a rough open-pored titanium coating,which could be produced by air plasma spraying, a combination comprisinga rough open-pored titanium coating and a HA top layer is alsoconceivable. The contacting parts could be made of a self lubricatedmaterial such as a waxy polymer, such as PTFE, PFA, FEP, PE and UHMWPE,or a powder metallurgy material which could be infused with a lubricant,which preferably is a biocompatible lubricant such as a Hyaluronic acidderivate. It is also conceivable that the material of contacting partsor surfaces of the medical device herein is adapted to be constantly orintermittently lubricated. According to some embodiments the parts orportions of the medical device could comprise a combination of metalmaterials and/or carbon fibers and/or boron, a combination of metal andplastic materials, a combination of metal and carbon based material, acombination of carbon and plastic based material, a combination offlexible and stiff materials, a combination of elastic and less elasticmaterials, Corian or acrylic polymers.

Please note that any embodiment or part of embodiment as well as anymethod or part of method could be combined in any way. All examplesherein should be seen as part of the general description and thereforepossible to combine in any way in general terms.

1-120. (canceled)
 121. A kit of locking members for implantation in ahip joint of a patient, the hip joint having a caput femur integratedwith a collum femur having a center axis extending longitudinal alongthe collum and caput femur in the center thereof, wherein said kit oflocking members comprises at least a first and second locking member,wherein: a. said first locking member comprises an element adapted tolock said artificial caput femur surface to at least one of a caput andcollum femur having a first size, such that the caput femur of the firstsize remains clasped and restrained in said artificial caput femursurface, and b. said second locking member comprises an element adaptedto lock said artificial caput femur surface to at least one of a caputand collum femur having a second different size, such that the caputfemur of the second size remains clasped and restrained in saidartificial caput femur surface.
 122. The kit of locking membersaccording to claim 121, wherein said first size is larger than saidsecond size.
 123. The kit of locking members according to claim 121,wherein said first locking member is larger than said second lockingmember.
 124. The kit of locking members according to claim 121, whereineach of said first and second locking members comprises a loop-shapedelement adapted to be connected in situ for creating said loop shapesurrounding the caput and/or collum femur, when implanted.
 125. The kitof locking members according to claim 121, wherein each of said firstand second locking member comprises a loop-shaped element adapted to beconnected in situ for creating said loop shape surrounding the caputand/or collum femur, when implanted.
 126. The kit of locking membersaccording to claim 125, wherein the first loop-shaped element has alarger diameter than the second loop-shaped element, when implanted.127. The kit of locking members according to claim 126, wherein each ofsaid first and second loop shaped element is adapted to have a firstlocking state, in which said loop shape has a first inner circumference,and a second locking state, in which said loop shape has a secondsmaller inner circumference.
 128. The kit of locking members accordingto claim 125, wherein said loop shaped element is an element selectedfrom: a cord, a wire and a band.
 129. The kit of locking membersaccording to claim 121, wherein: a. said first locking member is adaptedto lock the artificial caput femur surface, to the caput femur and/orcollum femur, and b. said second locking member is adapted to lock theartificial caput femur surface tighter to the caput femur and/or collumfemur.
 130. The kit of locking members according to claim 121, whereinsaid first and second locking member comprises a first and secondengagement member, and wherein said first engagement member is adaptedto engage said second engagement member, when implanted.
 131. The kit oflocking members according to claim 130, wherein said first and secondengagement members are adapted to mechanically self-connect byintroducing a male part of said first engagement member into a femalepart of said second engagement member.
 132. The kit of locking membersaccording to claim 130, wherein said first and second engagement membersare fixated to the artificial caput femur surface on the inside thereof.133. The kit of locking members according to claim 125, wherein saidloop shaped element comprises a first and second end, and wherein saidfirst and second ends are adapted to be connected to form said loopshaped element using an engagement member comprising two pivotablelocking parts.
 134. The kit of locking members according to claim 1,wherein at least one of said first and second locking member is madefrom an elastic material, for enabling the locking member to be placedonto the artificial caput femur surface, clasping the caput and/orcollum femur.